Interpretive Summary: Arcobacter are oxygen-tolerant bacteria which have been implicated in human and in animal diseases. Arcobacter spp. are closely related to and resemble Campylobacter fetus, which causes abortion in livestock. Since livestock infected with C. fetus may not be exported from the U.S., it is important for diagnostic laboratories to differentiate species of Campylobacter from Arcobacter. To this end, several campylobacter-like organisms recovered from porcine abortion cases in North Carolina were examined. These organisms did not react in a diagnostic test for Campylobacter and were characterized as Arcobacter based on their oxygen tolerance. We also recovered Arcobacter from porcine abortion cases in Iowa. The sensitivity of conventional biochemical identification methods was compared with DNA fingerprinting to identify the types of Arcobacter. Arcobacter butzleri (weak catalase reaction) and A. cryaerophilus (strong catalase reaction) were identified biochemically. However, the two subgroups of A. cryaerophilus were distinguished only by DNA fingerprints. This indicates DNA-based assays are useful to veterinary diagnostic laboratories for identification of Arcobacter recovered from livestock. This information can be used in determining the prevalence of Arcobacter in livestock abortion.

Technical Abstract:
Organisms resembling Campylobacter now designated as Arcobacter have been described from aborted farm animals in Europe and Canada and from cases of human enteritis in the United States, Thailand, and Australia. The goals of this study were: (1) to attempt to recover Arcobacter spp. from cases of porcine abortion, (2) to characterize these isolates by phenotype and ribotype, and (3) to compare the ability of ribotype and phenotype to separate Arcobacter butzleri and the 2 hybridization groups of A. cryaerophilus. Isolates of Arcobacter from North Carolina and Iowa were recovered from porcine tissues. In Iowa, Arcobacter were recovered from 43% (13/30) of porcine abortion cases evaluated. Isolations were made from placenta (42%), kidney (46%), and stomach contents (12%) which were the only specimens examined. The most reliable tests to phenotype A. butzleri included: growth in 1% glycine and in 1.5% NaCl, weak catalase activity, and resistance to cadmium chloride. Arcobacter cryaerophilus strains were characterized by strong catalase activity and sensitivity to cadmium chloride. The 2 subgroups of A. cryaerophilus could not be distinguished by phenotypic tests. This represents the first report of Arcobacter sp. isolated from swine in Iowa and the first description of A. cryaerophilus DNA group 1A in animals within the United States.